Epidemiological and clinical features of idiopathic pulmonary alveolar proteinosis in Japan

Idiopathic pulmonary alveolar proteinosis (IPAP) is a rare disease characterized by excessive amounts of lipoproteinaceous material in the alveolus. This report presents an interim analysis of nationwide epidemiological data from Japanese patients with pulmonary alveolar proteinosis, and the roles of serum markers for IPAP. (i) The nationwide demographic data from 166 Japanese patients with IPAP are shown. The female to male ratio was 1:2, and the average age was 51 +/- 14 years old (age range: 15-79 years) at registration or diagnosis. A total of 30% of patients with IPAP have a poor clinical course. In total, 30% of patients were treated with whole lung lavage therapy (WLL). Under WLL, the patients significantly improved in the short term, but 40% of the patients who underwent WLL worsened again. A new strategy such as granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy for intractable PAP is required. (ii) The correlation of serum KL-6, carcinoembryonic antigen, surfactant proteins D and A, and LDH with disease severity suggests their potential as disease markers. In contrast, serum anti-GM-CSF antibody did not correlate with disease severity, but is a specific marker for the diagnosis of IPAP. The combined measurements of the serum markers may well prove very useful for both the diagnosis and the management of IPAP patients.